1. Field of the Invention
The present invention relates to systems used for recovering fluids from subterranean wellbore and, more particularly, to systems that use multiple pumps to recover fluids from multiple subterranean earthen formations.
2. Setting of the Invention
In order to more completely drain older hydrocarbon bearing formations, it is now becoming common for an operator to drill one or more lateral boreholes from an existing wellbore. These lateral boreholes extend outwards from the existing wellbore at different depths and over different lengths to recover hydrocarbon fluids from one or more hydrocarbon bearing formations. Since each formation may have different reservoir conditions, as well as different fluid characteristics, there is a need to control the flow of fluids from each of the lateral boreholes and the existing borehole.
Currently, the control of the fluid recovery from these lateral wellbores is accomplished by placing a plurality of adjustable chokes, valves or sliding sleeves along a production tubing set within the wellbore adjacent each lateral wellbore. Each lateral wellbore is fluidicly isolated by placing production packers across the main wellbore between each lateral wellbore. Fluids from each lateral wellbore pass through the respective valve and into the production tubing, and are then recovered to the earth's surface. Control of the recovery of the fluids from each lateral wellbore is accomplished from the earth's surface by the independent opening and closing of the downhole valves in response to the fluid mixtures recovered to the earth's surface or by downhole sensors.
Additional control of the fluid recovery from the wellbore is provided by controlling the fluid production rate of a pumping system set within the wellbore, such as traveling valve pump or an electric submergible pumping system. The primary way to control the fluid production rate is by adjusting the speed of the pump's motor.
A significant problem with the foregoing fluid recovery systems is that a single pump has been used and thereby there is a limited draw down pressure available across all of the lateral wellbores. As each downhole valve is opened necessarily there is a reduction of the draw down pressure available for that and the other lateral wellbores. There is a need for a fluid recovery system that will allow fluid recovery from each lateral wellbore to be independently controlled and also provide adequate draw down pressure for each lateral wellbore.